A power generation device is a medium for transforming energy into electrical power. The energy source may be wind, water, fire and other natural forces. In addition to power generation devices that convert natural energy into electrical energy, there are also devices that generate power by a user himself/herself. An example is hand-operated power generating devices. However, such devices may be inefficient, laborious and inconvenient, and provide a relatively low generating capacity. Another example is power generation shoes. Piezoelectric-type power generation shoes, however, may have the similar issue with low power output and may include complicated circuitry.